Magnetic chuck.



. G. G. PRAGST.

MAGNETIC CHUCK.

APPLICATION HLED NOV. 9. 1914.

Y Patnted Jan.16,1917.

I 2 SHEETS+-SHEET 2.

Z 9 Wzi'nessea. jnv e nior'.

AZZorn ey Y Be it known that I, GEORGE .the city and county of Providence and State "STATES PATENT OFFICE.

GEORGE PBAGST, OF PROVIDENCE, BHODE ISLAND, LSSIGNOR'TO D. & W. FUSE COMPANY, OF PROVIDENCE, RHODE ISLAND, 1A CORPORATION OF RHODE ISLAND.

MAGNETIC CHUCK.

To all whom it mag concern:

Gr. PRAGST, of

of Rhode Island, have invented certain new and useful Improvements in Magnetic Chucks; and I do hereby declare the following specification, taken in connection with the accompanyin drawings, forming a part. a full, clear, and exact.

of the same, to

description thereof.

The invention relates to improvements in magnetic chucks and has for its primary object'to provide means whereby face plates having any desired design of polar surface I may be employed.

Another objectof the invention is to provide means whereby the leakage in the flow of the magnetic lines is materially lessened and an increased flow of the magnetic flux drawings,

through the work is efiected.

Another object 'of the invention is to greatly simplify and thereby cheapen the cost of manufacturing the chuck, as well-as to increase its efliciency.

To these ends the invention consists in the novel constructionilcombination and ar ereinafter' described rangement of parts set forth in the and more particularly claims.

While m improvements are applicable to -ma etic c ucks in general, they will be descri d in connection with a rotary magnetic chuck.

In describing the invention in detail reference will be made to the accompanying in which- Figure 1 is a plan view of the face of my improved chuck with face-plate attached.

Fig. 2 is a side view of the same. Fig. 3 is a plan view of the chuck with face-plate removed and a portion of the center-plate broken away. Fig. 4 is a longitudinal section on line at, m, Fig. 1. Fig. 5 is a plan view of a modified form of face-plate. Fig. 6 is a sectional view on line 3 y, Fig. 5. Fig. 7 is a plan view of another modified form offace-plate. Fig. 8 isa longitudinal section on line a, z, Fig. 7.

Referring to the drawings, 1 represents .the shell or casing. of the chuck which is preferably formed from cast-iron and prowashers 16'.

the flange 3 arranged vided' with an inwardly extending hollow Specification of Letters Patent. Patented J an, 16, 1917, Application filed November 9, 1914. Serial No. 872,977. 7 l I hub or central projection 2 and an external annular flange 3 extending toward the face of the chuck and forming an annular recess Fig. 4. Secured to or cast upon the rear of .55 4 between said hub and flange, as shown in the shell 1 is a series of threaded studs 5 I collector-rings 8 and 9 of copper or other conducting material are mounted on ring 6 and held in position thereon by means ofescutcheon-pins 10. The collector-rings 8 and 9 receive theelectric current from a suitable source through brushes 8 and 9" and deliver the same to a magnet-coil 11 through the magnet-coil leads 12, 12. a

The magnet-coil 11 isannular in shape and is located in the annuiar recess 4, where it is held against revolution in the shell'by' means of a stop 13 which projects from the said coil over the legs 14 of the stop.

stop 13 is arranged to engage a slot or recess 15 upon the outer surface of the hub 2,- as shown in Fi 3 and 4. Secured upon the free end of t e hub 2 by means of screws 16 is a circular steel plate 17 carrying upon its periphery a brass ring 18, which is prefera 1y forced thereon by hydraulic pressure. The screws 16 are provided with lead The outer periphery of is arranged to engage the inner periphery of and the outer face of said ring 18 is arranged flush with'the free end of said flange 3, as shown in Fig. 4. A brass'bush- Secured to the free end of the flange 3 by means of screws 20 is a face plate or work-.

holding plate 21, which portion 22 provided with pear-shaped 1 comprises a body a series of radially or wedge-shaped inner periphery of the coil and is secured to the brass ring 18 v opening's23, shown in Fig. 1. as nine in number, which are arranged with their narrow ends extending toward the center of the plate. It is preferred to have a certain number of the openings 23 extend in close proximity to the center of the plate 21 and to provide said plate with a central hole or opening 24, which furnishes means for centering the work.- Extending around the periphery of the face-plate 21 is an inwardly extending flange 25 which corresponds in circumference and has its free end adapted to register with the free end of flange 3'.

Mounted in each of the pear-shaped open- 'ings 23-is a pear-shaped pole piece 26 which responding oppositely disposed groove on channel 29, as shown n Fig. 4. The ole pieces 26 extend inwardly so as to be ush with the free end of'the flange 25 and are each provided with an undercut end portion 30. The-inner end of each of the pole pieces 26 is provided with an enlarged cha r.

nelor concaved portion 31.

'In assemblin the pole pieces '26 in the openings 23, t e face-plate is laid face downward, the pole pieces inserted in the openings 23 and the non-magnetic .rnaterial is poured into the openings surround ing the a pole pieces in a molten state from the rear.

side of the faceplate. By reason of the fact that the pole pieces are provided with the --undercut-end portion 30, the openings surrounding the pole pieces are-wider uponthe rear'side of the face-plate and thus greatly facilitate the insertionv of non-magnetic material. It will be seen that "the non-magnetic material-willenter the grooves 28 and 29 and thereby lock the pole pieces in en-- gagement with the body portion of the faceplate. It will also be seen that a suflicient amount of the non-ma etic material 27 is poured into the rear side of the face-plate to fill up the body portion flush with the free end of flange 25, thereby providing non-magnetic sections 32 between the pole pieces. When the face-plate 21 is secured to the flange 3 of the chuck, it will be seen that the pole pieces 26 engage the steel plate 17 and that the non-magneticmaterial 27 will register with the brass ring 18 throughout the entire surface of its outer face.

With the face-plate secured in position upon the chuck, the magnetic coil energized,

and a pieceof work applied to the faceplate so as to bridge across the non-magnetic material surrounding the pole-pieces, I

the magnetic flux will flow through the plate 17, pole pieces 26, work piece, not shown, flange 25 of face-plate 21, flange 3, shell 1 and hub 2 back to plate 17.

With the above construction, it will be seen that the plate'17' constitutes asingle pole piece with which a plurality of extension pole pieces 26 may register andthat the flange 3 constitutes a single opposite pole.

It will also be-seen that the single brass ring 18 which separates decreasethe length of the non-magnetic material, of which said ring is composed, thereby greatly decreasing the liability of leakage at this point. It will also be seen that by making the width of the non-magnetic material 27 surroundin extension pole pieces 26 wider at the rear liability of leakage at this decreased and an increased flux through the work will oint is greatly ow ofmagnetic be effected. It

will also be seen that with a single pole piece 17, which extends throughout the entire area of that portion of the chuck between the central opening and theinner periphery of the brass ring 18, face plates may be employed havln an almost unlimited number of designs 0 polar surface, and two such dlfi'erent designsare shown in Figs. 5 and 7. Fig. 5 shows a modified form of faceplate whlch is provided with a series of rav.dially extending T-slots 33, which are adapted-to receive means for'holding and centermgthe work. a

I Fig. 7 shows another modified form of v face-,plate,-1n which the pole pieces 26 arearranged' concentrically around. the faceplate nstead of radially. Itlis evident that any desireddesign. of. face-platamay be employed depending upon the character ofthe work to beheld uponthe chuck, it simply being; necessary that the pole pieces rest upon thepole-plate 17 and that the body portion of the face-plate contact only with the flange 3 on the shell Thus it will be seenthat no registering means are neceslsary to insure the proper registry of the pole pieces of thevface-plate with the poles of the chuck-body andthat no care need be used in applying the face-plate or in substituting one face-plate for another.

What I claim as my invention and desire .to secure by Letters Patent is:

1. An article of the character described, com rising a shell having an inwardly extending hollow hub, an inwardly extending peripheral flange and anannular. recess be said poles is coni str cted'and arranged to increase the width the face-plate,

tween said hub and flange, a magnet-coil in said recess, a pole-plate secured upon the free end of said hub and having a central openingv and a strip of non-magnetic'mate-V rial secured upon the periphery and arranged to engage the inner periphery of the 1 flange, and a'bushing extending through the central opening in said pole-plate and hollow hub.

2. A work-holding plate for a magnetic chuck, comprising a plate of magnetic material having a series of openings therein and an inwardly extending peripheral flange, pole pieces in said openings having their inner faces flush with the free end of said flange and held in said openings by nonmagnetic material.

3. A work-holding plate for a magnetic chuck,'comprising a plate of magneti'c material having a series of openings therein and an inwardly extending peripheral flange, pole pieces. in said openings having their inner faces flush with the free end of said flange and a seam of'non-magnetic material interposed between the pole piecesand theplate and filling the interior of the plate surrounding the pole pieces flush with said free end of the flange.

4. A magnetic chuck comprising a single pole of one polarity and a single pole of the opposite polarity, and a'work-holding plate having a plurality of pole pieces mounted therein and adapted to contact with one of said poles and a portion adapted to contact with the other pole.

5. A magnetic chuck comprising a single pole of one polarity and a single pole of the opposite polarity, and a work-holding plate having a plurality of pole-pieces adapted to contact with one of said poles and a portion adapted to contact with ;the other pole, with non-magnetic material located between said work-holding plate and said firstmen tioned pole.

6. A magnetic chuck comprising a central pole-plate of one polarity and aperipheral pole-piece of the opposite polarity, non-magnetic material between the. same, and a work holding plate having a plurality of polepieces all contacting with said central poleplate, a portion of the work-holding plate contacting with said peripheral pole-piece and non-magnetic material between said work-holding plate and said central poleplate.

7. A magnetic chuck comprising a shell the work-holding plate and said single poleplate. 7

GEORGE G. PRAGST. Witnesses W. H. Tnrms'ron, J. H. THURSTON. 

